Sprockets, sometimes called sprocket-wheels, are tools used in many mechanical processes, particularly for the purpose of transferring rotational force into motion. They are an excellent and necessary investment for customers in many industries, including automotive, industrial manufacturing, agriculture and forestry, electronics and film. Similar to gears, they are simple, thin cylindrical wheels with toothed rims. While gears require the partnership of other toothed parts to transmit motion, sprockets only need mesh or to interlock with indented or perforated materials, such as tracks or chains, to perform. Sprockets are also quite similar to pulleys as well, except that pulleys are smooth, while sprockets have teeth.
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Sprocket Design and Customization
Sprockets may be made from a wide variety of materials, depending on their application. For example, for use with food processing and/or high temperature applications, the best suited sprockets are made of stainless steel. Meanwhile, flat wire conveyor belts benefit the most from cast iron sprockets. Plastics like polyethylene, polyurethane, and nylon are reserved for continuous use at high temperatures.
Of all the materials used in conjunction with sprockets, chains are the most common. In this context, chains may be described as a sequence of joined links, flexible in one direction only, used to transfer power in machinery by enmeshing itself with the machine’s sprockets. Chains used with sprockets are usually made of a metal like alloy steel, plain carbon, or, where lubrication is an issue, brass or stainless steel. While it is also possible for chains to be made of a plastic such as nylon, this practice is inherently rare because of standards of design and interchangeability set forth by organizations like the American National Standards Institute (ANSI). Other than chains, sprockets are commonly meshed with tracks, specifically with continuous tracks, also called caterpillar tracks or tank tread. These tracks can be defined as a system of vehicle propulsion, or force leading to movement, in which continuous track plates are driven by two or more wheels. Tracks used with sprockets are generally either made of synthetic rubber, reinforced with steel wire, or modular steel plates, depending on the application. Manufacturers may choose to cut sprockets using either the English or the metric system of dimensions.
Manufacturing Process of Sprockets
Just as their configuration and function are similar to gears, sprockets are also fabricated using the same basic same methods as gears. For example, both gears and sprockets undergo hobbing, though sprockets experience it more routinely than gears. Sprocket hobbing is a cutting technique that uses a broaching machine to cut grooves, called teeth, into the sprocket.
In addition to making teeth, the goal of hobbing is to fortify sprockets so they can endure vigorous and repetitive use. Because broaching machines are capable of cutting a wide variety of tooth sizes and tooth amounts, the method of sprocket hobbing is applied to a diverse range of sprocket types. Other machining processes, like drilling, are used to perfect sprocket teeth and secure the closest tolerances possible, while secondary processes like hand finishing and heat treating may or may not be applied to increase a sprocket’s degrees of quality and strength.
Notable Types of Sprockets
Sprockets are available in a wide variety of types, such as:
- Roller Chain
- Timing Belt Sprockets
Film sprockets are sprockets specifically used to advance film through different mechanisms, like film projectors or video cameras. They perform this function by engaging and meshing with the perforations, or holes, that line both sides of the film strip. Film sprockets are also sometimes used similarly with paper, to advance punched tape or move the paper feed of computer printers. The purpose of idler sprockets is, in power transmission applications, to prevent excessive chain wear, whipping, or vibration, as well as to help obtain and maintain proper chain tension. They also have applications in brewing.
Roller chain sprockets, like their cousin the idler sprocket, are used frequently in power transmission. As their name suggests, roller chain sprockets are generally paired with roller chains, also called bush roller chains, to facilitate the transmission of mechanical power on all kinds of industrial, agricultural and domestic vehicles, electric motors, and machinery. They are lightweight and durable. Split sprockets are a bit different than all the rest; instead of being one solid piece, they are fabricated as two pieces. This design allows them to be installed and detached quickly and easily without taking apart any other part of the machinery, such as the shaft bearings. Lastly, timing belt sprockets, also known as synchronous sprockets, are made to allow for timed or synchronized, highly precise, non-slip power transmission. They provide high torque capabilities and facilitate high levels of efficiency.